A Study in Secrets
by blueskydog
Summary: Molly Hooper is the world's only consulting detective. Mary Morstan is an Army nurse returned to civilian life. Each carry secrets that, if revealed, could change the way the world sees them. But perhaps more important than what the world sees is what they see in each other. As their lives become entwined through mystery and danger, secrets may become a luxury they can't afford.
1. Prologue

Mary sat up in a panic, heart pounding and lungs aching for air. She brought a shaky hand to her face to wipe the sweat from her forehead and forced her breathing to slow into long, soothing breaths. The images of blood and gore clung to the corners of her mind as she slowly rose from bed. The jagged shadows in the dark room did nothing to ease her mind of the dark thoughts that haunted her dreams.

It's over, she told herself. It's all over. No more. You've done your part and you don't have to worry about it anymore.

She shivered, though, because she knew no matter how many times she said it, those words would never quite ring true. Because they weren't.

0~0~0

Before her return, Mary had thought PTSD was something only soldiers had to worry about. But as her family noticed her growing increasingly antisocial, she had fallen into a panic. Of course she had to pretend that it was merely the stress of coming home after years away from London. Desperately she sought out a remedy for her increasingly erratic mood swings. She dreaded the day when someone would ask her what was wrong—what, exactly, she had been up to in her years away from home. Before that day she hoped to rid herself of the traumas she had suffered. No one had to know what she had been doing. Let them all believe that she was simply an army nurse returned home. There was no harm in them believing in that half-truth if it was the best way to keep everyone from harm.

It was not a lie, and if it was, it was the whitest lie she could think of.

Besides, everyone has their secrets.


	2. Molly

Molly Hooper peered through the microscope at the DNA sample she'd procured from the lab. She carefully adjusted the lens until she could make out all the details she needed and smiled to herself. It was as she'd expected; a perfect match to the sample she'd been storing for days. If that was the case, then it could not possibly belong to the real killer; it was a decoy, one that had unfortunately been successful in duping Lestrade and his team. Lucky for them Molly had intervened. As she'd suspected from the beginning, the man they now held in jail had been framed. The evidence had been obvious, but she knew Lestrade had his hands tied when it came to Molly's deductions. Far from not believing her, he was simply unable to make decisions based on them, and so Molly often was forced to meticulously prove what she already knew. She wouldn't have minded at all if it was not such an infernal waste of time. The Yard would not wait for her, and quickly as she was capable of working, many a suspect had undergone unfair treatment in the time it took Molly to prove herself when all the time she knew they were innocent.

"Could you hand me the other slide, please?" she asked the pathologist standing next to her. When he didn't reply she glance up at him and was surprised to see he was staring at her again.

"Erm…Sherlock," she said awkwardly.

The dark-haired pathologist blinked, then straightened himself up and cleared his throat. "Yes, Ms. Hooper?" he muttered.

"I've told you before, you can call me Molly," she chided him.

"Yes, of course," Sherlock said as he made his way to the other side of the lab table to pick up the slide she'd asked for. "Habits." He handed her the slide.  
Molly took it. "We've only known each other going on three months now—as long as I've been coming in her," she said. "It can't be that much of a habit."

Knowing that Sherlock would not know what to say, she pretended to drop the subject as she replaced the DNA sample under the microscope with a new one. Busily taking notes as she worked, she kept one ear cocked to listen as Sherlock continued his own work in the lab with his autopsy instruments. It was easy enough for her to brush aside the tension in favor of her work, but she was aware that Sherlock had more difficulties dealing with his emotions. Some described his bluntness and insensitivity as "psychopathic," but Molly knew that he felt more than he let on.

She had just finished her work and had begun to pack away her things when the door to the lab opened and two people walked in. Sherlock glanced up with an annoyed expression on his face; absorbed in an autopsy like a teenager absorbed in a mystery novel, he hated being interrupted, especially by people who apparently did not belong in the lab. And Molly could tell neither of these people were regulars. For one thing, the first one was an acquaintance of hers, Mike Stanford; though he was a medical student and it was not bizarre that he would wander into the lab at St. Bart's. The other Molly had never seen before, but after giving her a once-over she saw all she needed to gather that she, no doubt, had a very good reason for being here as well.

"Mike," she greeted as he came into ear shot.

Mike smiled and nodded. "Molly, nice to see you. Here, this is an old friend of mine, Mary Morstan."

Molly put down her bag and approached the blond woman to shake her hand. "Nice to meet you, Mary. I'm Molly Hooper," she said.

Mary's smile was genuine, if a bit nervous, and she gave Molly's hand a brief shake before dropping it. Her eyes wandered unconsciously around the room, taking in the lab instruments, Sherlock at his autopsy, and Molly's half-packed experiment at the other table. In an attempt to break the awkward silence Molly spoke up.

"So, you're here about the room, are you? What have you thought so far?" she inquired.

Mary turned back to her, startled, then looked to Mike. "You told her already? I didn't see you text anyone."

Mike gave Mary an amused smile. "I didn't."

"I surmised," Molly said almost apologetically. "I'd only just mentioned my situation to Mike this morning after not seeing him for weeks, and here he shows up out of the blue with a person I've never met before, who happens to be in a similar situation as myself. Sorry if I startled you, but it's all straightforward if you think of it."

Mary again looked confused, her brow furrowed as she glanced from Mike to Molly. "What do you mean—a similar situation?" she asked in a voice suggesting she was guarding herself carefully. Molly hurriedly tried to reassure her.

"Oh, I only mean in that we're both looking for a place to stay at a reasonable price, given we're both a bit short on cash, with no family to turn to—a common enough situation, and fortunate for both of us that we've found each other," she added, hoping Mary didn't take her statement too personally.

"But—" Mary stared at Molly. "How…did you know about my…uh…situation?"

Molly glanced at the clock and saw it was almost six. "Oh, it doesn't really matter," she said, making her way to her bag to finish packing away her instruments. "We're both on the same boat. So I bet we're a good enough match. I'm moving in tomorrow at nine. Mrs. Hudson gave me the key, so I can meet you there around then? Otherwise just knock and she'll let you in. She's an awful dear, Mrs. Hudson is. Sorry to cut you off but I have to get going, I have an appointment with a client in fifteen. I'll see you tomorrow then?" She smiled encouragingly as she zipped up her bag. Mary continued to stare at her for whatever reason. Not wanting to be rude, but still in a hurry, Molly nodded once at her and walked out of the lab.


	3. Mary

"I told you she was odd," Mike said.

Mary stood rigid where Molly had left her. "You could have been a bit more specific," she said tersely. "How did she know so much about me?"

"Search me." Mike shrugged. "If you're living with her, you'll find out quicker than I."

Despite herself Mary couldn't help the smile quirking at her lips. Molly seemed nice enough, and if a mystery it was, well, she'd always loved a good mystery. But as Mike led her out of the lab, the twinge of fear returned when she thought of Molly Hooper's searching eyes scan her from head to foot, and the seemingly effortless way she had rattled off facts about her as if she'd heard everything about her.

"You're sure you've never mentioned me to her?" Mary asked Mike.

"Not even in passing," Mike assured her. "We've rarely spoken beyond morbid lab chats. She's not much of a conversationalist."

Mary nodded and followed her friend down the white hallways of the hospital. She did need a flat mate, but one could only go so far with a complete stranger. And if Molly could already know so much about her, who was to say she wouldn't find out even more about Mary?

What if she already knew?

0~0~0

Mary packed her bags the next morning—she had a remarkably small amount of possessions—and took a cab to Baker Street. She was there by five till nine. Setting her two bags down she leaned against the lamp post and pulled out her phone to see if she'd received any messages. She felt a slight twinge in her stomach when she saw there were none. She told herself it was relief. Her past was behind her now, and so were her relationships.

But how had Molly known that?

Another cab pulled up just as Mary's drove off, and Mary looked up to see Molly stepping onto the curb carrying a box, with several bags dangling by their straps from her arms. Pocketing her phone Mary hurried over and took the box from the smaller woman. "Here, let me get that for you," she said. She was startled by its weight when Molly let go and fought not to drop it. Gingerly she hefted it onto her hip to free her right arm.

"Thank you," Molly said with a tired smile. "I'm sorry I have so many things, but when you have a job like mine it's hard to throw things out."

Mary was tempted to blurt out "And what is your job?" but knew this was not the right time. "It's no trouble, I only have two bags myself," she said instead. "I bet we can make it up in one trip."

Molly's brown eyes fell on Mary's two bags and she laughed. "At least one of us has self-control," she said. "I have heaps of clothes still sitting at the hotel waiting for me to check out with them." With her now free hand she reached into her pocket and pulled out her key. Mary slung her two bags on her right shoulder and followed Molly as she unlocked the door marked 221 B. Molly had to push the door open with her knee but the two of them managed to step into the dimly lit building without dropping anything. Mary shut the door with her elbow as Molly began to climb a set of stairs.

"Ours is upstairs," she said over her shoulder. Mary nodded and followed her, taking in the details of the place. Dark wooden floors and an incredibly ugly wall paper pattern made the place seem vaguely unfriendly. The intense quiet surprised her, as she'd expected to hear some noise from the neighbors. All she could hear was the slow creaking of the stairs as Molly made her way up, and the faint sound of vehicles outside. Mary hefted the box a bit higher on her side and climbed the narrow stairs to the door Molly was opening. Molly smiled at her as she again kicked the door open and stepped into the flat. Mary shifted sideways so the box wouldn't hit the door frame as she followed her new flat mate in.

"Well, here we are," Molly said, setting her bags down on the well-worn, but well-cleaned sofa. "It's not Buckingham Palace but I think it will do, don't you?"

Mary looked around and smiled. It was a small place, with the same dark wood floors and ugly wallpaper, but the furniture was soft and cozy looking and everything was clean. The windows gleamed in the misty afternoon light and the rug before the hearth was spotless. She glanced into the kitchen and saw it was well organized, the refrigerator already humming and the surfaces shining.

"There's two bedrooms, one upstairs and down," Molly spoke up, already unzipping her bags and pulling out pile upon piles of books. "I have no preference myself but if it's all the same, if I could take the downstairs—it's just I work late some nights, all nights actually, and it would be better if I weren't clunking up and down the stairs while you're trying to sleep—"

"That's fine," Mary said. She set the box carefully down on the coffee table, which was already sweetly bedecked with hand-crocheted coasters. "I didn't have any preconceived notions about it. Upstairs is fine with me."

Molly didn't look up from her work, but Mary saw the smile of relief pass over her face. Mary set her bags on the floor and walked over to the smaller set of stairs leading up to what would be her room. Walking up, she noticed these stairs didn't creak half as much, and was relived, as she was somewhat of a restless sleeper herself and wouldn't want to disturb Molly if she had to go down for tea in the middle of the night.

She opened the door at the top of the stares and was greeted by the sight of more dark wood floors, but thankfully a much more plain, simple white wallpaper. The single bed was spread with a patchwork quilt and the fluffed-up pillows looked so inviting Mary had to fight the urge to fling herself on them right then and there. Next to the bed was a simple nightstand; opposite the door was a closet. It was tiny but homey, and for Mary it was the perfect topper to a heretofore only acceptable accommodation. Mrs. Hudson obviously had taken great care to prepare the flat for their arrival, and such attention to detail was a wonderful asset to any landlady. Up till now Mary had been nervous about sharing the flat with a stranger, but seeing the easy privacy the bedroom allowed her, alone at the top of the stairs, she felt immediately safe.

She walked over to the window and pushed aside the shade to look out. Below her lay Baker Street in all its foggy glory. She could see people bustling about below her, and felt a sudden surge of strength when she thought, _They can't see me._

A cry of "Molly, darling!" from below broke her out of her reverie, and Mary walked quickly back downstairs to see who had entered the flat. When she walked back into the sitting room, she saw a tiny old lady with her arms around Molly. Molly was hugged her back before drawing away and giving her an affectionate peck on the cheek. Mary couldn't help smiling at the sight.

"Hello," she greeted as the elderly woman turned to her with a soft, sweet face. "You must be Mrs. Hudson?"

"Yes, and you must be Mary!" Mrs. Hudson said. She shook Mary's offered hand and beamed up at her. "Molly dear has told me about you. You'll make a fine pair up here, I'm sure. I've known Molly since she was just a little thing and a sweeter little girl you've never met—"

"Mrs. H.," Molly interrupted, face red with embarrassment. "I'm not a little girl."

"Of course not, dear," Mrs. Hudson relented. "But Mary should have no worries, you'll be like two peas in a pod, I can tell already!"

"I'm glad to hear it," Mary said. Personally she felt Mrs. Hudson was probably exaggerating a bit. While she wanted to be friendly with Molly, it was rare Mary got very close to anyone. She had too much baggage at her age, and no one really understood. Besides, there was always that part of her she kept hidden, and most people did not like to have things kept from them. All she asked of Molly was a safe haven at a reasonable price and no questions. All they had to do was coexist. She needed, and wanted, nothing more than that.

"Well, dear, I'll let you both get settled then," Mrs. Hudson said. "Moving in can be hard, so just give me a holler if you need anything! And when you're all done, come down for some tea, and we can have a nice housewarming chat." She smiled at them once again before waving and heading out the door. Mary noticed as she left that she limped slightly. Molly saw her watching and spoke softly.

"She has hip problems—nothing major, but stairs can be a bit of a nuisance for her. If you do need help I'd rather do it myself than have you call her, she's such a dear and I don't want her over-exerting herself."

"Thanks, but I think I can handle myself," Mary said. It came out sharper than she'd intended, and she felt a pang of regret when Molly flushed again and quickly turned away. Molly had the best intentions, and Mary knew she was trying to be helpful. But there was part of her that still felt an offer of help threatened her own authority.

_I can do it myself…I don't need help._

An awkward silence followed as the two women set about unpacking their things. Mary carried her bags upstairs and began laying her things in order, but her ear continually batted out to the room below her as she listened to Molly slowly and methodically organizing her belongings. What all was she in possession of, anyway? Mary had seen a lot of scientific equipment in the room, which was not surprising, since she had met Molly in a lab. But what exactly was her profession? Was she actually a medical student? But why would a medical student have "clients"?

Mary shook her head and tried to focus on her own possessions. She didn't need to know any more about Molly than Molly knew about her. And yet something about the woman fascinated Mary, and she longed to know more about her—and how the devil she knew what she did about Mary.

She had just finished putting her clothing in the closet when she heard a buzz at the door. Surprised, she cocked an ear and heard Molly leap up from the floor and make her way to the door. Mary closed her closet and walked back downstairs just as Molly opened the door and let in Mrs. Hudson, who was wringing her hands worriedly.

"Molly dear, there's a detective at the door and he says he needs to see you—is there anything I should know-?"

"Oh! It's Lestrade," Molly said quickly. "No need to worry, Mrs. Hudson, he's a friend. You can let him in"

Mrs. Hudson pursed her lips, unsure, but nodded and turned back to call in the visitor. Mary stood at the bottom of the stairs and looked at Molly, who glanced back at her.

"Detective Inspector Lestrade," she said. "He sometimes needs my advice for some of his cases."

"What are you?" The words just fell out of Mary's mouth. She regretted it instantly, since it sounded not only rude but stupid. Thankfully Molly seemed not to have heard her, as just then a man walked in and shook hands with Molly.

"Sorry to bother you, as you've just moved in," he said, glancing around the room. "But we've found another one, and I wanted you to come and see it."

Molly nodded as if what the man said made perfect sense and flew to the couch, rummaging through her things as if looking for something in particular. The man turned to Mary.

"Hello," he said. "DI Lestrade. You must be Molly's-?"

"I'm her new flat mate," Mary said, sensing Lestrade about to insinuate something different. He nodded and held out his hand for her to shake. She did so hesitantly, knowing he was merely being polite and was not really interested in introductions. "I'm Mary."

"Nice to meet you." He seemed genuine enough, but his eyes trailed over to where Molly still knelt by the couch. Her rummaging had become more violent. Finally her head popped out of her box, strands of hair floating about her face like planets orbiting the sun that was her head.

"I'm terribly sorry, Lestrade, I just can't seem to find my phone. I just moved in and I'm afraid I left it back in the hotel with my clothes—you know how much I use the phone when it comes to a crime scene—"

"You can use mine." Again the words just dropped out of Mary's mouth before she could think. All of the words they'd been throwing around—_another one, detective, crime scene—_were starting to madden her with curiosity.

She didn't think of how bad an idea this probably was. Already her hand was reaching into her pocket as Lestrade and Molly turned to her. She felt a jolt of fear but calmed when she repeated to herself what she already knew. _You deleted it all, there's nothing incriminating on there. She can't learn anything more than she already knows._

"But I couldn't just take it," Molly protested. "It's yours, and I'll get it all mucked up with my pictures and notes."

Mary shrugged and lifted the phone from her pocket. "I'll just text them to you when you're done and then delete it, once you find yours."

Molly looked intensely relieved but still doubtful as she said, "I'd hate to be a bother—"

"No bother at all. I can even come along, so if you have problems with it I can help. If that's alright," she added quickly when Lestrade's expression darkened.

"I'm already stretching things letting Molly interfere," he said.

"Mary won't be any trouble," Molly said. "If Donovan gives you a hard time about it, remind her who's case this even is." She rose to her feet and yanked the band from her ponytail and commence to retie it into a neat bun as she headed for the door. "Thank you very much, Mary."

"Of course." Mary followed her and the detective out the door. Maybe now she'd get the chance to see just who Molly Hooper was.


End file.
